Already known are cleaning systems for a food or beverage preparation cavity in which food or a beverage is prepared. Thus, in cooking ovens such as, convection and combi ovens, a cleaning detergent is sprayed into an oven cavity via a pump and pipe system. As shown in FIG. 1, a known cooking oven 20 comprises an enclosure 22 that defines an oven cavity 24. A cleaning system 26 includes a detergent reservoir 28 and a rinse reservoir 30 connected in a pipe system 32 via a detergent pump 34 and a neutralizer pump 36. Pipe system 32 is connected to a nozzle 38 and a rotor 40 in an upper part of oven cavity 24. With neutralizer pump 36 off, detergent pump 34 is turned on to supply detergent to oven cavity 24 via nozzle 38 and rotor 40. After a spray-in-phase, the detergent reacts with the soil and is then flushed with water via a separate pipe 42 and a water valve 46 via nozzles 44 and 48. In one of the last steps, with detergent pump 34 off, neutralizer pump 36 is turned on to supply neutralizer fluid so as to flush pipe system 32 with food safe rinse fluid (or also called neutralizer fluid) in order to get all detergent out of pipe system 32. This step is important, because if the detergent is not flushed, this fluid might drop out of pipe system 32 in the following cooking steps. All of the fluids and water exit the oven cavity 24 by a bottom drain hole 50 to a drain reservoir 52 and drain pipe 54.
A disadvantage of the cleaning system of the known cooking oven is that the pipe system, even after the rinse step, may still be filled because the pipe system is closed and does not allow the fluid to escape immediately. After a later cooking step this remaining fluid will thermally expand, thereby resulting in dripping.